1 /* $OpenBSD: sshd.c,v 1.567 2021/01/09 12:10:02 dtucker Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <stdarg.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #ifdef WITH_OPENSSL 68 #include <openssl/bn.h> 69 #endif 70 71 #include "xmalloc.h" 72 #include "ssh.h" 73 #include "ssh2.h" 74 #include "sshpty.h" 75 #include "packet.h" 76 #include "log.h" 77 #include "sshbuf.h" 78 #include "misc.h" 79 #include "match.h" 80 #include "servconf.h" 81 #include "uidswap.h" 82 #include "compat.h" 83 #include "cipher.h" 84 #include "digest.h" 85 #include "sshkey.h" 86 #include "kex.h" 87 #include "myproposal.h" 88 #include "authfile.h" 89 #include "pathnames.h" 90 #include "atomicio.h" 91 #include "canohost.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "authfd.h" 95 #include "msg.h" 96 #include "dispatch.h" 97 #include "channels.h" 98 #include "session.h" 99 #include "monitor.h" 100 #ifdef GSSAPI 101 #include "ssh-gss.h" 102 #endif 103 #include "monitor_wrap.h" 104 #include "ssh-sandbox.h" 105 #include "auth-options.h" 106 #include "version.h" 107 #include "ssherr.h" 108 #include "sk-api.h" 109 #include "srclimit.h" 110 111 /* Re-exec fds */ 112 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 113 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 114 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 115 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 116 117 extern char *__progname; 118 119 /* Server configuration options. */ 120 ServerOptions options; 121 122 /* Name of the server configuration file. */ 123 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 124 125 /* 126 * Debug mode flag. This can be set on the command line. If debug 127 * mode is enabled, extra debugging output will be sent to the system 128 * log, the daemon will not go to background, and will exit after processing 129 * the first connection. 130 */ 131 int debug_flag = 0; 132 133 /* 134 * Indicating that the daemon should only test the configuration and keys. 135 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 136 * configuration, optionally using connection information provided by the 137 * "-C" flag. 138 */ 139 static int test_flag = 0; 140 141 /* Flag indicating that the daemon is being started from inetd. */ 142 static int inetd_flag = 0; 143 144 /* Flag indicating that sshd should not detach and become a daemon. */ 145 static int no_daemon_flag = 0; 146 147 /* debug goes to stderr unless inetd_flag is set */ 148 static int log_stderr = 0; 149 150 /* Saved arguments to main(). */ 151 static char **saved_argv; 152 153 /* re-exec */ 154 static int rexeced_flag = 0; 155 static int rexec_flag = 1; 156 static int rexec_argc = 0; 157 static char **rexec_argv; 158 159 /* 160 * The sockets that the server is listening; this is used in the SIGHUP 161 * signal handler. 162 */ 163 #define MAX_LISTEN_SOCKS 16 164 static int listen_socks[MAX_LISTEN_SOCKS]; 165 static int num_listen_socks = 0; 166 167 /* Daemon's agent connection */ 168 int auth_sock = -1; 169 static int have_agent = 0; 170 171 /* 172 * Any really sensitive data in the application is contained in this 173 * structure. The idea is that this structure could be locked into memory so 174 * that the pages do not get written into swap. However, there are some 175 * problems. The private key contains BIGNUMs, and we do not (in principle) 176 * have access to the internals of them, and locking just the structure is 177 * not very useful. Currently, memory locking is not implemented. 178 */ 179 struct { 180 struct sshkey **host_keys; /* all private host keys */ 181 struct sshkey **host_pubkeys; /* all public host keys */ 182 struct sshkey **host_certificates; /* all public host certificates */ 183 int have_ssh2_key; 184 } sensitive_data; 185 186 /* This is set to true when a signal is received. */ 187 static volatile sig_atomic_t received_sighup = 0; 188 static volatile sig_atomic_t received_sigterm = 0; 189 190 /* session identifier, used by RSA-auth */ 191 u_char session_id[16]; 192 193 /* same for ssh2 */ 194 u_char *session_id2 = NULL; 195 u_int session_id2_len = 0; 196 197 /* record remote hostname or ip */ 198 u_int utmp_len = HOST_NAME_MAX+1; 199 200 /* 201 * startup_pipes/flags are used for tracking children of the listening sshd 202 * process early in their lifespans. This tracking is needed for three things: 203 * 204 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 205 * connections. 206 * 2) Avoiding a race condition for SIGHUP processing, where child processes 207 * may have listen_socks open that could collide with main listener process 208 * after it restarts. 209 * 3) Ensuring that rexec'd sshd processes have received their initial state 210 * from the parent listen process before handling SIGHUP. 211 * 212 * Child processes signal that they have completed closure of the listen_socks 213 * and (if applicable) received their rexec state by sending a char over their 214 * sock. Child processes signal that authentication has completed by closing 215 * the sock (or by exiting). 216 */ 217 static int *startup_pipes = NULL; 218 static int *startup_flags = NULL; /* Indicates child closed listener */ 219 static int startup_pipe = -1; /* in child */ 220 221 /* variables used for privilege separation */ 222 int use_privsep = -1; 223 struct monitor *pmonitor = NULL; 224 int privsep_is_preauth = 1; 225 226 /* global connection state and authentication contexts */ 227 Authctxt *the_authctxt = NULL; 228 struct ssh *the_active_state; 229 230 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 231 struct sshauthopt *auth_opts = NULL; 232 233 /* sshd_config buffer */ 234 struct sshbuf *cfg; 235 236 /* Included files from the configuration file */ 237 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 238 239 /* message to be displayed after login */ 240 struct sshbuf *loginmsg; 241 242 /* Prototypes for various functions defined later in this file. */ 243 void destroy_sensitive_data(void); 244 void demote_sensitive_data(void); 245 static void do_ssh2_kex(struct ssh *); 246 247 static char *listener_proctitle; 248 249 /* 250 * Close all listening sockets 251 */ 252 static void 253 close_listen_socks(void) 254 { 255 int i; 256 257 for (i = 0; i < num_listen_socks; i++) 258 close(listen_socks[i]); 259 num_listen_socks = -1; 260 } 261 262 static void 263 close_startup_pipes(void) 264 { 265 int i; 266 267 if (startup_pipes) 268 for (i = 0; i < options.max_startups; i++) 269 if (startup_pipes[i] != -1) 270 close(startup_pipes[i]); 271 } 272 273 /* 274 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 275 * the effect is to reread the configuration file (and to regenerate 276 * the server key). 277 */ 278 279 /*ARGSUSED*/ 280 static void 281 sighup_handler(int sig) 282 { 283 received_sighup = 1; 284 } 285 286 /* 287 * Called from the main program after receiving SIGHUP. 288 * Restarts the server. 289 */ 290 static void 291 sighup_restart(void) 292 { 293 logit("Received SIGHUP; restarting."); 294 if (options.pid_file != NULL) 295 unlink(options.pid_file); 296 close_listen_socks(); 297 close_startup_pipes(); 298 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 299 execv(saved_argv[0], saved_argv); 300 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 301 strerror(errno)); 302 exit(1); 303 } 304 305 /* 306 * Generic signal handler for terminating signals in the master daemon. 307 */ 308 /*ARGSUSED*/ 309 static void 310 sigterm_handler(int sig) 311 { 312 received_sigterm = sig; 313 } 314 315 /* 316 * SIGCHLD handler. This is called whenever a child dies. This will then 317 * reap any zombies left by exited children. 318 */ 319 /*ARGSUSED*/ 320 static void 321 main_sigchld_handler(int sig) 322 { 323 int save_errno = errno; 324 pid_t pid; 325 int status; 326 327 debug("main_sigchld_handler: %s", strsignal(sig)); 328 329 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 330 (pid == -1 && errno == EINTR)) 331 ; 332 errno = save_errno; 333 } 334 335 /* 336 * Signal handler for the alarm after the login grace period has expired. 337 */ 338 /*ARGSUSED*/ 339 static void 340 grace_alarm_handler(int sig) 341 { 342 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 343 kill(pmonitor->m_pid, SIGALRM); 344 345 /* 346 * Try to kill any processes that we have spawned, E.g. authorized 347 * keys command helpers. 348 */ 349 if (getpgid(0) == getpid()) { 350 ssh_signal(SIGTERM, SIG_IGN); 351 kill(0, SIGTERM); 352 } 353 354 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 355 /* Log error and exit. */ 356 sigdie("Timeout before authentication for %s port %d", 357 ssh_remote_ipaddr(the_active_state), 358 ssh_remote_port(the_active_state)); 359 } 360 361 /* Destroy the host and server keys. They will no longer be needed. */ 362 void 363 destroy_sensitive_data(void) 364 { 365 u_int i; 366 367 for (i = 0; i < options.num_host_key_files; i++) { 368 if (sensitive_data.host_keys[i]) { 369 sshkey_free(sensitive_data.host_keys[i]); 370 sensitive_data.host_keys[i] = NULL; 371 } 372 if (sensitive_data.host_certificates[i]) { 373 sshkey_free(sensitive_data.host_certificates[i]); 374 sensitive_data.host_certificates[i] = NULL; 375 } 376 } 377 } 378 379 /* Demote private to public keys for network child */ 380 void 381 demote_sensitive_data(void) 382 { 383 struct sshkey *tmp; 384 u_int i; 385 int r; 386 387 for (i = 0; i < options.num_host_key_files; i++) { 388 if (sensitive_data.host_keys[i]) { 389 if ((r = sshkey_from_private( 390 sensitive_data.host_keys[i], &tmp)) != 0) 391 fatal_r(r, "could not demote host %s key", 392 sshkey_type(sensitive_data.host_keys[i])); 393 sshkey_free(sensitive_data.host_keys[i]); 394 sensitive_data.host_keys[i] = tmp; 395 } 396 /* Certs do not need demotion */ 397 } 398 } 399 400 static void 401 privsep_preauth_child(void) 402 { 403 gid_t gidset[1]; 404 struct passwd *pw; 405 406 /* Enable challenge-response authentication for privilege separation */ 407 privsep_challenge_enable(); 408 409 #ifdef GSSAPI 410 /* Cache supported mechanism OIDs for later use */ 411 ssh_gssapi_prepare_supported_oids(); 412 #endif 413 414 /* Demote the private keys to public keys. */ 415 demote_sensitive_data(); 416 417 /* Demote the child */ 418 if (getuid() == 0 || geteuid() == 0) { 419 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 420 fatal("Privilege separation user %s does not exist", 421 SSH_PRIVSEP_USER); 422 pw = pwcopy(pw); /* Ensure mutable */ 423 endpwent(); 424 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 425 426 /* Change our root directory */ 427 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 428 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 429 strerror(errno)); 430 if (chdir("/") == -1) 431 fatal("chdir(\"/\"): %s", strerror(errno)); 432 433 /* 434 * Drop our privileges 435 * NB. Can't use setusercontext() after chroot. 436 */ 437 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 438 (u_int)pw->pw_gid); 439 gidset[0] = pw->pw_gid; 440 if (setgroups(1, gidset) == -1) 441 fatal("setgroups: %.100s", strerror(errno)); 442 permanently_set_uid(pw); 443 } 444 } 445 446 static int 447 privsep_preauth(struct ssh *ssh) 448 { 449 int status, r; 450 pid_t pid; 451 struct ssh_sandbox *box = NULL; 452 453 /* Set up unprivileged child process to deal with network data */ 454 pmonitor = monitor_init(); 455 /* Store a pointer to the kex for later rekeying */ 456 pmonitor->m_pkex = &ssh->kex; 457 458 if (use_privsep == PRIVSEP_ON) 459 box = ssh_sandbox_init(); 460 pid = fork(); 461 if (pid == -1) { 462 fatal("fork of unprivileged child failed"); 463 } else if (pid != 0) { 464 debug2("Network child is on pid %ld", (long)pid); 465 466 pmonitor->m_pid = pid; 467 if (have_agent) { 468 r = ssh_get_authentication_socket(&auth_sock); 469 if (r != 0) { 470 error_r(r, "Could not get agent socket"); 471 have_agent = 0; 472 } 473 } 474 if (box != NULL) 475 ssh_sandbox_parent_preauth(box, pid); 476 monitor_child_preauth(ssh, pmonitor); 477 478 /* Wait for the child's exit status */ 479 while (waitpid(pid, &status, 0) == -1) { 480 if (errno == EINTR) 481 continue; 482 pmonitor->m_pid = -1; 483 fatal_f("waitpid: %s", strerror(errno)); 484 } 485 privsep_is_preauth = 0; 486 pmonitor->m_pid = -1; 487 if (WIFEXITED(status)) { 488 if (WEXITSTATUS(status) != 0) 489 fatal_f("preauth child exited with status %d", 490 WEXITSTATUS(status)); 491 } else if (WIFSIGNALED(status)) 492 fatal_f("preauth child terminated by signal %d", 493 WTERMSIG(status)); 494 if (box != NULL) 495 ssh_sandbox_parent_finish(box); 496 return 1; 497 } else { 498 /* child */ 499 close(pmonitor->m_sendfd); 500 close(pmonitor->m_log_recvfd); 501 502 /* Arrange for logging to be sent to the monitor */ 503 set_log_handler(mm_log_handler, pmonitor); 504 505 privsep_preauth_child(); 506 setproctitle("%s", "[net]"); 507 if (box != NULL) 508 ssh_sandbox_child(box); 509 510 return 0; 511 } 512 } 513 514 static void 515 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 516 { 517 if (authctxt->pw->pw_uid == 0) { 518 /* File descriptor passing is broken or root login */ 519 use_privsep = 0; 520 goto skip; 521 } 522 523 /* New socket pair */ 524 monitor_reinit(pmonitor); 525 526 pmonitor->m_pid = fork(); 527 if (pmonitor->m_pid == -1) 528 fatal("fork of unprivileged child failed"); 529 else if (pmonitor->m_pid != 0) { 530 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 531 sshbuf_reset(loginmsg); 532 monitor_clear_keystate(ssh, pmonitor); 533 monitor_child_postauth(ssh, pmonitor); 534 535 /* NEVERREACHED */ 536 exit(0); 537 } 538 539 /* child */ 540 541 close(pmonitor->m_sendfd); 542 pmonitor->m_sendfd = -1; 543 544 /* Demote the private keys to public keys. */ 545 demote_sensitive_data(); 546 547 /* Drop privileges */ 548 do_setusercontext(authctxt->pw); 549 550 skip: 551 /* It is safe now to apply the key state */ 552 monitor_apply_keystate(ssh, pmonitor); 553 554 /* 555 * Tell the packet layer that authentication was successful, since 556 * this information is not part of the key state. 557 */ 558 ssh_packet_set_authenticated(ssh); 559 } 560 561 static void 562 append_hostkey_type(struct sshbuf *b, const char *s) 563 { 564 int r; 565 566 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 567 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 568 return; 569 } 570 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 571 fatal_fr(r, "sshbuf_putf"); 572 } 573 574 static char * 575 list_hostkey_types(void) 576 { 577 struct sshbuf *b; 578 struct sshkey *key; 579 char *ret; 580 u_int i; 581 582 if ((b = sshbuf_new()) == NULL) 583 fatal_f("sshbuf_new failed"); 584 for (i = 0; i < options.num_host_key_files; i++) { 585 key = sensitive_data.host_keys[i]; 586 if (key == NULL) 587 key = sensitive_data.host_pubkeys[i]; 588 if (key == NULL) 589 continue; 590 switch (key->type) { 591 case KEY_RSA: 592 /* for RSA we also support SHA2 signatures */ 593 append_hostkey_type(b, "rsa-sha2-512"); 594 append_hostkey_type(b, "rsa-sha2-256"); 595 /* FALLTHROUGH */ 596 case KEY_DSA: 597 case KEY_ECDSA: 598 case KEY_ED25519: 599 case KEY_ECDSA_SK: 600 case KEY_ED25519_SK: 601 case KEY_XMSS: 602 append_hostkey_type(b, sshkey_ssh_name(key)); 603 break; 604 } 605 /* If the private key has a cert peer, then list that too */ 606 key = sensitive_data.host_certificates[i]; 607 if (key == NULL) 608 continue; 609 switch (key->type) { 610 case KEY_RSA_CERT: 611 /* for RSA we also support SHA2 signatures */ 612 append_hostkey_type(b, 613 "rsa-sha2-512-cert-v01@openssh.com"); 614 append_hostkey_type(b, 615 "rsa-sha2-256-cert-v01@openssh.com"); 616 /* FALLTHROUGH */ 617 case KEY_DSA_CERT: 618 case KEY_ECDSA_CERT: 619 case KEY_ED25519_CERT: 620 case KEY_ECDSA_SK_CERT: 621 case KEY_ED25519_SK_CERT: 622 case KEY_XMSS_CERT: 623 append_hostkey_type(b, sshkey_ssh_name(key)); 624 break; 625 } 626 } 627 if ((ret = sshbuf_dup_string(b)) == NULL) 628 fatal_f("sshbuf_dup_string failed"); 629 sshbuf_free(b); 630 debug_f("%s", ret); 631 return ret; 632 } 633 634 static struct sshkey * 635 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 636 { 637 u_int i; 638 struct sshkey *key; 639 640 for (i = 0; i < options.num_host_key_files; i++) { 641 switch (type) { 642 case KEY_RSA_CERT: 643 case KEY_DSA_CERT: 644 case KEY_ECDSA_CERT: 645 case KEY_ED25519_CERT: 646 case KEY_ECDSA_SK_CERT: 647 case KEY_ED25519_SK_CERT: 648 case KEY_XMSS_CERT: 649 key = sensitive_data.host_certificates[i]; 650 break; 651 default: 652 key = sensitive_data.host_keys[i]; 653 if (key == NULL && !need_private) 654 key = sensitive_data.host_pubkeys[i]; 655 break; 656 } 657 if (key == NULL || key->type != type) 658 continue; 659 switch (type) { 660 case KEY_ECDSA: 661 case KEY_ECDSA_SK: 662 case KEY_ECDSA_CERT: 663 case KEY_ECDSA_SK_CERT: 664 if (key->ecdsa_nid != nid) 665 continue; 666 /* FALLTHROUGH */ 667 default: 668 return need_private ? 669 sensitive_data.host_keys[i] : key; 670 } 671 } 672 return NULL; 673 } 674 675 struct sshkey * 676 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 677 { 678 return get_hostkey_by_type(type, nid, 0, ssh); 679 } 680 681 struct sshkey * 682 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 683 { 684 return get_hostkey_by_type(type, nid, 1, ssh); 685 } 686 687 struct sshkey * 688 get_hostkey_by_index(int ind) 689 { 690 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 691 return (NULL); 692 return (sensitive_data.host_keys[ind]); 693 } 694 695 struct sshkey * 696 get_hostkey_public_by_index(int ind, struct ssh *ssh) 697 { 698 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 699 return (NULL); 700 return (sensitive_data.host_pubkeys[ind]); 701 } 702 703 int 704 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 705 { 706 u_int i; 707 708 for (i = 0; i < options.num_host_key_files; i++) { 709 if (sshkey_is_cert(key)) { 710 if (key == sensitive_data.host_certificates[i] || 711 (compare && sensitive_data.host_certificates[i] && 712 sshkey_equal(key, 713 sensitive_data.host_certificates[i]))) 714 return (i); 715 } else { 716 if (key == sensitive_data.host_keys[i] || 717 (compare && sensitive_data.host_keys[i] && 718 sshkey_equal(key, sensitive_data.host_keys[i]))) 719 return (i); 720 if (key == sensitive_data.host_pubkeys[i] || 721 (compare && sensitive_data.host_pubkeys[i] && 722 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 723 return (i); 724 } 725 } 726 return (-1); 727 } 728 729 /* Inform the client of all hostkeys */ 730 static void 731 notify_hostkeys(struct ssh *ssh) 732 { 733 struct sshbuf *buf; 734 struct sshkey *key; 735 u_int i, nkeys; 736 int r; 737 char *fp; 738 739 /* Some clients cannot cope with the hostkeys message, skip those. */ 740 if (ssh->compat & SSH_BUG_HOSTKEYS) 741 return; 742 743 if ((buf = sshbuf_new()) == NULL) 744 fatal_f("sshbuf_new"); 745 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 746 key = get_hostkey_public_by_index(i, ssh); 747 if (key == NULL || key->type == KEY_UNSPEC || 748 sshkey_is_cert(key)) 749 continue; 750 fp = sshkey_fingerprint(key, options.fingerprint_hash, 751 SSH_FP_DEFAULT); 752 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 753 free(fp); 754 if (nkeys == 0) { 755 /* 756 * Start building the request when we find the 757 * first usable key. 758 */ 759 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 760 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 761 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 762 sshpkt_fatal(ssh, r, "%s: start request", __func__); 763 } 764 /* Append the key to the request */ 765 sshbuf_reset(buf); 766 if ((r = sshkey_putb(key, buf)) != 0) 767 fatal_fr(r, "couldn't put hostkey %d", i); 768 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 769 sshpkt_fatal(ssh, r, "%s: append key", __func__); 770 nkeys++; 771 } 772 debug3_f("sent %u hostkeys", nkeys); 773 if (nkeys == 0) 774 fatal_f("no hostkeys"); 775 if ((r = sshpkt_send(ssh)) != 0) 776 sshpkt_fatal(ssh, r, "%s: send", __func__); 777 sshbuf_free(buf); 778 } 779 780 /* 781 * returns 1 if connection should be dropped, 0 otherwise. 782 * dropping starts at connection #max_startups_begin with a probability 783 * of (max_startups_rate/100). the probability increases linearly until 784 * all connections are dropped for startups > max_startups 785 */ 786 static int 787 should_drop_connection(int startups) 788 { 789 int p, r; 790 791 if (startups < options.max_startups_begin) 792 return 0; 793 if (startups >= options.max_startups) 794 return 1; 795 if (options.max_startups_rate == 100) 796 return 1; 797 798 p = 100 - options.max_startups_rate; 799 p *= startups - options.max_startups_begin; 800 p /= options.max_startups - options.max_startups_begin; 801 p += options.max_startups_rate; 802 r = arc4random_uniform(100); 803 804 debug_f("p %d, r %d", p, r); 805 return (r < p) ? 1 : 0; 806 } 807 808 /* 809 * Check whether connection should be accepted by MaxStartups. 810 * Returns 0 if the connection is accepted. If the connection is refused, 811 * returns 1 and attempts to send notification to client. 812 * Logs when the MaxStartups condition is entered or exited, and periodically 813 * while in that state. 814 */ 815 static int 816 drop_connection(int sock, int startups, int notify_pipe) 817 { 818 char *laddr, *raddr; 819 const char msg[] = "Exceeded MaxStartups\r\n"; 820 static time_t last_drop, first_drop; 821 static u_int ndropped; 822 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 823 time_t now; 824 825 now = monotime(); 826 if (!should_drop_connection(startups) && 827 srclimit_check_allow(sock, notify_pipe) == 1) { 828 if (last_drop != 0 && 829 startups < options.max_startups_begin - 1) { 830 /* XXX maybe need better hysteresis here */ 831 logit("exited MaxStartups throttling after %s, " 832 "%u connections dropped", 833 fmt_timeframe(now - first_drop), ndropped); 834 last_drop = 0; 835 } 836 return 0; 837 } 838 839 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 840 if (last_drop == 0) { 841 error("beginning MaxStartups throttling"); 842 drop_level = SYSLOG_LEVEL_INFO; 843 first_drop = now; 844 ndropped = 0; 845 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 846 /* Periodic logs */ 847 error("in MaxStartups throttling for %s, " 848 "%u connections dropped", 849 fmt_timeframe(now - first_drop), ndropped + 1); 850 drop_level = SYSLOG_LEVEL_INFO; 851 } 852 last_drop = now; 853 ndropped++; 854 855 laddr = get_local_ipaddr(sock); 856 raddr = get_peer_ipaddr(sock); 857 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 858 "past MaxStartups", startups, raddr, get_peer_port(sock), 859 laddr, get_local_port(sock)); 860 free(laddr); 861 free(raddr); 862 /* best-effort notification to client */ 863 (void)write(sock, msg, sizeof(msg) - 1); 864 return 1; 865 } 866 867 static void 868 usage(void) 869 { 870 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 871 fprintf(stderr, 872 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 873 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 874 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 875 ); 876 exit(1); 877 } 878 879 static void 880 send_rexec_state(int fd, struct sshbuf *conf) 881 { 882 struct sshbuf *m = NULL, *inc = NULL; 883 struct include_item *item = NULL; 884 int r; 885 886 debug3_f("entering fd = %d config len %zu", fd, 887 sshbuf_len(conf)); 888 889 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 890 fatal_f("sshbuf_new failed"); 891 892 /* pack includes into a string */ 893 TAILQ_FOREACH(item, &includes, entry) { 894 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 895 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 896 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 897 fatal_fr(r, "compose includes"); 898 } 899 900 /* 901 * Protocol from reexec master to child: 902 * string configuration 903 * string included_files[] { 904 * string selector 905 * string filename 906 * string contents 907 * } 908 */ 909 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 910 (r = sshbuf_put_stringb(m, inc)) != 0) 911 fatal_fr(r, "compose config"); 912 if (ssh_msg_send(fd, 0, m) == -1) 913 error_f("ssh_msg_send failed"); 914 915 sshbuf_free(m); 916 sshbuf_free(inc); 917 918 debug3_f("done"); 919 } 920 921 static void 922 recv_rexec_state(int fd, struct sshbuf *conf) 923 { 924 struct sshbuf *m, *inc; 925 u_char *cp, ver; 926 size_t len; 927 int r; 928 struct include_item *item; 929 930 debug3_f("entering fd = %d", fd); 931 932 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 933 fatal_f("sshbuf_new failed"); 934 if (ssh_msg_recv(fd, m) == -1) 935 fatal_f("ssh_msg_recv failed"); 936 if ((r = sshbuf_get_u8(m, &ver)) != 0) 937 fatal_fr(r, "parse version"); 938 if (ver != 0) 939 fatal_f("rexec version mismatch"); 940 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 941 (r = sshbuf_get_stringb(m, inc)) != 0) 942 fatal_fr(r, "parse config"); 943 944 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 945 fatal_fr(r, "sshbuf_put"); 946 947 while (sshbuf_len(inc) != 0) { 948 item = xcalloc(1, sizeof(*item)); 949 if ((item->contents = sshbuf_new()) == NULL) 950 fatal_f("sshbuf_new failed"); 951 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 952 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 953 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 954 fatal_fr(r, "parse includes"); 955 TAILQ_INSERT_TAIL(&includes, item, entry); 956 } 957 958 free(cp); 959 sshbuf_free(m); 960 961 debug3_f("done"); 962 } 963 964 /* Accept a connection from inetd */ 965 static void 966 server_accept_inetd(int *sock_in, int *sock_out) 967 { 968 if (rexeced_flag) { 969 close(REEXEC_CONFIG_PASS_FD); 970 *sock_in = *sock_out = dup(STDIN_FILENO); 971 } else { 972 *sock_in = dup(STDIN_FILENO); 973 *sock_out = dup(STDOUT_FILENO); 974 } 975 /* 976 * We intentionally do not close the descriptors 0, 1, and 2 977 * as our code for setting the descriptors won't work if 978 * ttyfd happens to be one of those. 979 */ 980 if (stdfd_devnull(1, 1, !log_stderr) == -1) 981 error_f("stdfd_devnull failed"); 982 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 983 } 984 985 /* 986 * Listen for TCP connections 987 */ 988 static void 989 listen_on_addrs(struct listenaddr *la) 990 { 991 int ret, listen_sock; 992 struct addrinfo *ai; 993 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 994 995 for (ai = la->addrs; ai; ai = ai->ai_next) { 996 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 997 continue; 998 if (num_listen_socks >= MAX_LISTEN_SOCKS) 999 fatal("Too many listen sockets. " 1000 "Enlarge MAX_LISTEN_SOCKS"); 1001 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1002 ntop, sizeof(ntop), strport, sizeof(strport), 1003 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1004 error("getnameinfo failed: %.100s", 1005 ssh_gai_strerror(ret)); 1006 continue; 1007 } 1008 /* Create socket for listening. */ 1009 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1010 ai->ai_protocol); 1011 if (listen_sock == -1) { 1012 /* kernel may not support ipv6 */ 1013 verbose("socket: %.100s", strerror(errno)); 1014 continue; 1015 } 1016 if (set_nonblock(listen_sock) == -1) { 1017 close(listen_sock); 1018 continue; 1019 } 1020 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1021 verbose("socket: CLOEXEC: %s", strerror(errno)); 1022 close(listen_sock); 1023 continue; 1024 } 1025 /* Socket options */ 1026 set_reuseaddr(listen_sock); 1027 if (la->rdomain != NULL && 1028 set_rdomain(listen_sock, la->rdomain) == -1) { 1029 close(listen_sock); 1030 continue; 1031 } 1032 1033 debug("Bind to port %s on %s.", strport, ntop); 1034 1035 /* Bind the socket to the desired port. */ 1036 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1037 error("Bind to port %s on %s failed: %.200s.", 1038 strport, ntop, strerror(errno)); 1039 close(listen_sock); 1040 continue; 1041 } 1042 listen_socks[num_listen_socks] = listen_sock; 1043 num_listen_socks++; 1044 1045 /* Start listening on the port. */ 1046 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1047 fatal("listen on [%s]:%s: %.100s", 1048 ntop, strport, strerror(errno)); 1049 logit("Server listening on %s port %s%s%s.", 1050 ntop, strport, 1051 la->rdomain == NULL ? "" : " rdomain ", 1052 la->rdomain == NULL ? "" : la->rdomain); 1053 } 1054 } 1055 1056 static void 1057 server_listen(void) 1058 { 1059 u_int i; 1060 1061 /* Initialise per-source limit tracking. */ 1062 srclimit_init(options.max_startups, options.per_source_max_startups, 1063 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1064 1065 for (i = 0; i < options.num_listen_addrs; i++) { 1066 listen_on_addrs(&options.listen_addrs[i]); 1067 freeaddrinfo(options.listen_addrs[i].addrs); 1068 free(options.listen_addrs[i].rdomain); 1069 memset(&options.listen_addrs[i], 0, 1070 sizeof(options.listen_addrs[i])); 1071 } 1072 free(options.listen_addrs); 1073 options.listen_addrs = NULL; 1074 options.num_listen_addrs = 0; 1075 1076 if (!num_listen_socks) 1077 fatal("Cannot bind any address."); 1078 } 1079 1080 /* 1081 * The main TCP accept loop. Note that, for the non-debug case, returns 1082 * from this function are in a forked subprocess. 1083 */ 1084 static void 1085 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1086 { 1087 fd_set *fdset; 1088 int i, j, ret, maxfd; 1089 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1090 int startup_p[2] = { -1 , -1 }; 1091 char c = 0; 1092 struct sockaddr_storage from; 1093 socklen_t fromlen; 1094 pid_t pid; 1095 1096 /* setup fd set for accept */ 1097 fdset = NULL; 1098 maxfd = 0; 1099 for (i = 0; i < num_listen_socks; i++) 1100 if (listen_socks[i] > maxfd) 1101 maxfd = listen_socks[i]; 1102 /* pipes connected to unauthenticated child sshd processes */ 1103 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1104 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1105 for (i = 0; i < options.max_startups; i++) 1106 startup_pipes[i] = -1; 1107 1108 /* 1109 * Stay listening for connections until the system crashes or 1110 * the daemon is killed with a signal. 1111 */ 1112 for (;;) { 1113 if (ostartups != startups) { 1114 setproctitle("%s [listener] %d of %d-%d startups", 1115 listener_proctitle, startups, 1116 options.max_startups_begin, options.max_startups); 1117 ostartups = startups; 1118 } 1119 if (received_sighup) { 1120 if (!lameduck) { 1121 debug("Received SIGHUP; waiting for children"); 1122 close_listen_socks(); 1123 lameduck = 1; 1124 } 1125 if (listening <= 0) 1126 sighup_restart(); 1127 } 1128 free(fdset); 1129 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1130 sizeof(fd_mask)); 1131 1132 for (i = 0; i < num_listen_socks; i++) 1133 FD_SET(listen_socks[i], fdset); 1134 for (i = 0; i < options.max_startups; i++) 1135 if (startup_pipes[i] != -1) 1136 FD_SET(startup_pipes[i], fdset); 1137 1138 /* Wait in select until there is a connection. */ 1139 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1140 if (ret == -1 && errno != EINTR) 1141 error("select: %.100s", strerror(errno)); 1142 if (received_sigterm) { 1143 logit("Received signal %d; terminating.", 1144 (int) received_sigterm); 1145 close_listen_socks(); 1146 if (options.pid_file != NULL) 1147 unlink(options.pid_file); 1148 exit(received_sigterm == SIGTERM ? 0 : 255); 1149 } 1150 if (ret == -1) 1151 continue; 1152 1153 for (i = 0; i < options.max_startups; i++) { 1154 if (startup_pipes[i] == -1 || 1155 !FD_ISSET(startup_pipes[i], fdset)) 1156 continue; 1157 switch (read(startup_pipes[i], &c, sizeof(c))) { 1158 case -1: 1159 if (errno == EINTR || errno == EAGAIN) 1160 continue; 1161 if (errno != EPIPE) { 1162 error_f("startup pipe %d (fd=%d): " 1163 "read %s", i, startup_pipes[i], 1164 strerror(errno)); 1165 } 1166 /* FALLTHROUGH */ 1167 case 0: 1168 /* child exited or completed auth */ 1169 close(startup_pipes[i]); 1170 srclimit_done(startup_pipes[i]); 1171 startup_pipes[i] = -1; 1172 startups--; 1173 if (startup_flags[i]) 1174 listening--; 1175 break; 1176 case 1: 1177 /* child has finished preliminaries */ 1178 if (startup_flags[i]) { 1179 listening--; 1180 startup_flags[i] = 0; 1181 } 1182 break; 1183 } 1184 } 1185 for (i = 0; i < num_listen_socks; i++) { 1186 if (!FD_ISSET(listen_socks[i], fdset)) 1187 continue; 1188 fromlen = sizeof(from); 1189 *newsock = accept(listen_socks[i], 1190 (struct sockaddr *)&from, &fromlen); 1191 if (*newsock == -1) { 1192 if (errno != EINTR && errno != EWOULDBLOCK && 1193 errno != ECONNABORTED) 1194 error("accept: %.100s", 1195 strerror(errno)); 1196 if (errno == EMFILE || errno == ENFILE) 1197 usleep(100 * 1000); 1198 continue; 1199 } 1200 if (unset_nonblock(*newsock) == -1 || 1201 pipe(startup_p) == -1) 1202 continue; 1203 if (drop_connection(*newsock, startups, startup_p[0])) { 1204 close(*newsock); 1205 close(startup_p[0]); 1206 close(startup_p[1]); 1207 continue; 1208 } 1209 1210 if (rexec_flag && socketpair(AF_UNIX, 1211 SOCK_STREAM, 0, config_s) == -1) { 1212 error("reexec socketpair: %s", 1213 strerror(errno)); 1214 close(*newsock); 1215 close(startup_p[0]); 1216 close(startup_p[1]); 1217 continue; 1218 } 1219 1220 for (j = 0; j < options.max_startups; j++) 1221 if (startup_pipes[j] == -1) { 1222 startup_pipes[j] = startup_p[0]; 1223 if (maxfd < startup_p[0]) 1224 maxfd = startup_p[0]; 1225 startups++; 1226 startup_flags[j] = 1; 1227 break; 1228 } 1229 1230 /* 1231 * Got connection. Fork a child to handle it, unless 1232 * we are in debugging mode. 1233 */ 1234 if (debug_flag) { 1235 /* 1236 * In debugging mode. Close the listening 1237 * socket, and start processing the 1238 * connection without forking. 1239 */ 1240 debug("Server will not fork when running in debugging mode."); 1241 close_listen_socks(); 1242 *sock_in = *newsock; 1243 *sock_out = *newsock; 1244 close(startup_p[0]); 1245 close(startup_p[1]); 1246 startup_pipe = -1; 1247 pid = getpid(); 1248 if (rexec_flag) { 1249 send_rexec_state(config_s[0], cfg); 1250 close(config_s[0]); 1251 } 1252 return; 1253 } 1254 1255 /* 1256 * Normal production daemon. Fork, and have 1257 * the child process the connection. The 1258 * parent continues listening. 1259 */ 1260 listening++; 1261 if ((pid = fork()) == 0) { 1262 /* 1263 * Child. Close the listening and 1264 * max_startup sockets. Start using 1265 * the accepted socket. Reinitialize 1266 * logging (since our pid has changed). 1267 * We return from this function to handle 1268 * the connection. 1269 */ 1270 startup_pipe = startup_p[1]; 1271 close_startup_pipes(); 1272 close_listen_socks(); 1273 *sock_in = *newsock; 1274 *sock_out = *newsock; 1275 log_init(__progname, 1276 options.log_level, 1277 options.log_facility, 1278 log_stderr); 1279 if (rexec_flag) 1280 close(config_s[0]); 1281 else { 1282 /* 1283 * Signal parent that the preliminaries 1284 * for this child are complete. For the 1285 * re-exec case, this happens after the 1286 * child has received the rexec state 1287 * from the server. 1288 */ 1289 (void)atomicio(vwrite, startup_pipe, 1290 "\0", 1); 1291 } 1292 return; 1293 } 1294 1295 /* Parent. Stay in the loop. */ 1296 if (pid == -1) 1297 error("fork: %.100s", strerror(errno)); 1298 else 1299 debug("Forked child %ld.", (long)pid); 1300 1301 close(startup_p[1]); 1302 1303 if (rexec_flag) { 1304 close(config_s[1]); 1305 send_rexec_state(config_s[0], cfg); 1306 close(config_s[0]); 1307 } 1308 close(*newsock); 1309 } 1310 } 1311 } 1312 1313 /* 1314 * If IP options are supported, make sure there are none (log and 1315 * return an error if any are found). Basically we are worried about 1316 * source routing; it can be used to pretend you are somebody 1317 * (ip-address) you are not. That itself may be "almost acceptable" 1318 * under certain circumstances, but rhosts authentication is useless 1319 * if source routing is accepted. Notice also that if we just dropped 1320 * source routing here, the other side could use IP spoofing to do 1321 * rest of the interaction and could still bypass security. So we 1322 * exit here if we detect any IP options. 1323 */ 1324 static void 1325 check_ip_options(struct ssh *ssh) 1326 { 1327 int sock_in = ssh_packet_get_connection_in(ssh); 1328 struct sockaddr_storage from; 1329 u_char opts[200]; 1330 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1331 char text[sizeof(opts) * 3 + 1]; 1332 1333 memset(&from, 0, sizeof(from)); 1334 if (getpeername(sock_in, (struct sockaddr *)&from, 1335 &fromlen) == -1) 1336 return; 1337 if (from.ss_family != AF_INET) 1338 return; 1339 /* XXX IPv6 options? */ 1340 1341 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1342 &option_size) >= 0 && option_size != 0) { 1343 text[0] = '\0'; 1344 for (i = 0; i < option_size; i++) 1345 snprintf(text + i*3, sizeof(text) - i*3, 1346 " %2.2x", opts[i]); 1347 fatal("Connection from %.100s port %d with IP opts: %.800s", 1348 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1349 } 1350 return; 1351 } 1352 1353 /* Set the routing domain for this process */ 1354 static void 1355 set_process_rdomain(struct ssh *ssh, const char *name) 1356 { 1357 int rtable, ortable = getrtable(); 1358 const char *errstr; 1359 1360 if (name == NULL) 1361 return; /* default */ 1362 1363 if (strcmp(name, "%D") == 0) { 1364 /* "expands" to routing domain of connection */ 1365 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1366 return; 1367 } 1368 1369 rtable = (int)strtonum(name, 0, 255, &errstr); 1370 if (errstr != NULL) /* Shouldn't happen */ 1371 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1372 if (rtable != ortable && setrtable(rtable) != 0) 1373 fatal("Unable to set routing domain %d: %s", 1374 rtable, strerror(errno)); 1375 debug_f("set routing domain %d (was %d)", rtable, ortable); 1376 } 1377 1378 static void 1379 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1380 struct sshkey *key) 1381 { 1382 static struct ssh_digest_ctx *ctx; 1383 u_char *hash; 1384 size_t len; 1385 struct sshbuf *buf; 1386 int r; 1387 1388 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1389 fatal_f("ssh_digest_start"); 1390 if (key == NULL) { /* finalize */ 1391 /* add server config in case we are using agent for host keys */ 1392 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1393 sshbuf_len(server_cfg)) != 0) 1394 fatal_f("ssh_digest_update"); 1395 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1396 hash = xmalloc(len); 1397 if (ssh_digest_final(ctx, hash, len) != 0) 1398 fatal_f("ssh_digest_final"); 1399 options.timing_secret = PEEK_U64(hash); 1400 freezero(hash, len); 1401 ssh_digest_free(ctx); 1402 ctx = NULL; 1403 return; 1404 } 1405 if ((buf = sshbuf_new()) == NULL) 1406 fatal_f("could not allocate buffer"); 1407 if ((r = sshkey_private_serialize(key, buf)) != 0) 1408 fatal_fr(r, "decode key"); 1409 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1410 fatal_f("ssh_digest_update"); 1411 sshbuf_reset(buf); 1412 sshbuf_free(buf); 1413 } 1414 1415 static char * 1416 prepare_proctitle(int ac, char **av) 1417 { 1418 char *ret = NULL; 1419 int i; 1420 1421 for (i = 0; i < ac; i++) 1422 xextendf(&ret, " ", "%s", av[i]); 1423 return ret; 1424 } 1425 1426 /* 1427 * Main program for the daemon. 1428 */ 1429 int 1430 main(int ac, char **av) 1431 { 1432 struct ssh *ssh = NULL; 1433 extern char *optarg; 1434 extern int optind; 1435 int r, opt, on = 1, already_daemon, remote_port; 1436 int sock_in = -1, sock_out = -1, newsock = -1; 1437 const char *remote_ip, *rdomain; 1438 char *fp, *line, *laddr, *logfile = NULL; 1439 int config_s[2] = { -1 , -1 }; 1440 u_int i, j; 1441 u_int64_t ibytes, obytes; 1442 mode_t new_umask; 1443 struct sshkey *key; 1444 struct sshkey *pubkey; 1445 int keytype; 1446 Authctxt *authctxt; 1447 struct connection_info *connection_info = NULL; 1448 1449 /* Save argv. */ 1450 saved_argv = av; 1451 rexec_argc = ac; 1452 1453 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1454 sanitise_stdfd(); 1455 1456 /* Initialize configuration options to their default values. */ 1457 initialize_server_options(&options); 1458 1459 /* Parse command-line arguments. */ 1460 while ((opt = getopt(ac, av, 1461 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1462 switch (opt) { 1463 case '4': 1464 options.address_family = AF_INET; 1465 break; 1466 case '6': 1467 options.address_family = AF_INET6; 1468 break; 1469 case 'f': 1470 config_file_name = optarg; 1471 break; 1472 case 'c': 1473 servconf_add_hostcert("[command-line]", 0, 1474 &options, optarg); 1475 break; 1476 case 'd': 1477 if (debug_flag == 0) { 1478 debug_flag = 1; 1479 options.log_level = SYSLOG_LEVEL_DEBUG1; 1480 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1481 options.log_level++; 1482 break; 1483 case 'D': 1484 no_daemon_flag = 1; 1485 break; 1486 case 'E': 1487 logfile = optarg; 1488 /* FALLTHROUGH */ 1489 case 'e': 1490 log_stderr = 1; 1491 break; 1492 case 'i': 1493 inetd_flag = 1; 1494 break; 1495 case 'r': 1496 rexec_flag = 0; 1497 break; 1498 case 'R': 1499 rexeced_flag = 1; 1500 inetd_flag = 1; 1501 break; 1502 case 'Q': 1503 /* ignored */ 1504 break; 1505 case 'q': 1506 options.log_level = SYSLOG_LEVEL_QUIET; 1507 break; 1508 case 'b': 1509 /* protocol 1, ignored */ 1510 break; 1511 case 'p': 1512 options.ports_from_cmdline = 1; 1513 if (options.num_ports >= MAX_PORTS) { 1514 fprintf(stderr, "too many ports.\n"); 1515 exit(1); 1516 } 1517 options.ports[options.num_ports++] = a2port(optarg); 1518 if (options.ports[options.num_ports-1] <= 0) { 1519 fprintf(stderr, "Bad port number.\n"); 1520 exit(1); 1521 } 1522 break; 1523 case 'g': 1524 if ((options.login_grace_time = convtime(optarg)) == -1) { 1525 fprintf(stderr, "Invalid login grace time.\n"); 1526 exit(1); 1527 } 1528 break; 1529 case 'k': 1530 /* protocol 1, ignored */ 1531 break; 1532 case 'h': 1533 servconf_add_hostkey("[command-line]", 0, 1534 &options, optarg, 1); 1535 break; 1536 case 't': 1537 test_flag = 1; 1538 break; 1539 case 'T': 1540 test_flag = 2; 1541 break; 1542 case 'C': 1543 connection_info = get_connection_info(ssh, 0, 0); 1544 if (parse_server_match_testspec(connection_info, 1545 optarg) == -1) 1546 exit(1); 1547 break; 1548 case 'u': 1549 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1550 if (utmp_len > HOST_NAME_MAX+1) { 1551 fprintf(stderr, "Invalid utmp length.\n"); 1552 exit(1); 1553 } 1554 break; 1555 case 'o': 1556 line = xstrdup(optarg); 1557 if (process_server_config_line(&options, line, 1558 "command-line", 0, NULL, NULL, &includes) != 0) 1559 exit(1); 1560 free(line); 1561 break; 1562 case '?': 1563 default: 1564 usage(); 1565 break; 1566 } 1567 } 1568 if (rexeced_flag || inetd_flag) 1569 rexec_flag = 0; 1570 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1571 fatal("sshd re-exec requires execution with an absolute path"); 1572 if (rexeced_flag) 1573 closefrom(REEXEC_MIN_FREE_FD); 1574 else 1575 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1576 1577 #ifdef WITH_OPENSSL 1578 OpenSSL_add_all_algorithms(); 1579 #endif 1580 1581 /* If requested, redirect the logs to the specified logfile. */ 1582 if (logfile != NULL) 1583 log_redirect_stderr_to(logfile); 1584 /* 1585 * Force logging to stderr until we have loaded the private host 1586 * key (unless started from inetd) 1587 */ 1588 log_init(__progname, 1589 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1590 SYSLOG_LEVEL_INFO : options.log_level, 1591 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1592 SYSLOG_FACILITY_AUTH : options.log_facility, 1593 log_stderr || !inetd_flag || debug_flag); 1594 1595 sensitive_data.have_ssh2_key = 0; 1596 1597 /* 1598 * If we're not doing an extended test do not silently ignore connection 1599 * test params. 1600 */ 1601 if (test_flag < 2 && connection_info != NULL) 1602 fatal("Config test connection parameter (-C) provided without " 1603 "test mode (-T)"); 1604 1605 /* Fetch our configuration */ 1606 if ((cfg = sshbuf_new()) == NULL) 1607 fatal_f("sshbuf_new failed"); 1608 if (rexeced_flag) { 1609 setproctitle("%s", "[rexeced]"); 1610 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1611 if (!debug_flag) { 1612 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1613 close(REEXEC_STARTUP_PIPE_FD); 1614 /* 1615 * Signal parent that this child is at a point where 1616 * they can go away if they have a SIGHUP pending. 1617 */ 1618 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1619 } 1620 } else if (strcasecmp(config_file_name, "none") != 0) 1621 load_server_config(config_file_name, cfg); 1622 1623 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1624 cfg, &includes, NULL); 1625 1626 /* Fill in default values for those options not explicitly set. */ 1627 fill_default_server_options(&options); 1628 1629 /* challenge-response is implemented via keyboard interactive */ 1630 if (options.challenge_response_authentication) 1631 options.kbd_interactive_authentication = 1; 1632 1633 /* Check that options are sensible */ 1634 if (options.authorized_keys_command_user == NULL && 1635 (options.authorized_keys_command != NULL && 1636 strcasecmp(options.authorized_keys_command, "none") != 0)) 1637 fatal("AuthorizedKeysCommand set without " 1638 "AuthorizedKeysCommandUser"); 1639 if (options.authorized_principals_command_user == NULL && 1640 (options.authorized_principals_command != NULL && 1641 strcasecmp(options.authorized_principals_command, "none") != 0)) 1642 fatal("AuthorizedPrincipalsCommand set without " 1643 "AuthorizedPrincipalsCommandUser"); 1644 1645 /* 1646 * Check whether there is any path through configured auth methods. 1647 * Unfortunately it is not possible to verify this generally before 1648 * daemonisation in the presence of Match block, but this catches 1649 * and warns for trivial misconfigurations that could break login. 1650 */ 1651 if (options.num_auth_methods != 0) { 1652 for (i = 0; i < options.num_auth_methods; i++) { 1653 if (auth2_methods_valid(options.auth_methods[i], 1654 1) == 0) 1655 break; 1656 } 1657 if (i >= options.num_auth_methods) 1658 fatal("AuthenticationMethods cannot be satisfied by " 1659 "enabled authentication methods"); 1660 } 1661 1662 /* Check that there are no remaining arguments. */ 1663 if (optind < ac) { 1664 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1665 exit(1); 1666 } 1667 1668 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1669 1670 /* load host keys */ 1671 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1672 sizeof(struct sshkey *)); 1673 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1674 sizeof(struct sshkey *)); 1675 1676 if (options.host_key_agent) { 1677 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1678 setenv(SSH_AUTHSOCKET_ENV_NAME, 1679 options.host_key_agent, 1); 1680 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1681 have_agent = 1; 1682 else 1683 error_r(r, "Could not connect to agent \"%s\"", 1684 options.host_key_agent); 1685 } 1686 1687 for (i = 0; i < options.num_host_key_files; i++) { 1688 int ll = options.host_key_file_userprovided[i] ? 1689 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1690 1691 if (options.host_key_files[i] == NULL) 1692 continue; 1693 if ((r = sshkey_load_private(options.host_key_files[i], "", 1694 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1695 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1696 options.host_key_files[i]); 1697 if (sshkey_is_sk(key) && 1698 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1699 debug("host key %s requires user presence, ignoring", 1700 options.host_key_files[i]); 1701 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1702 } 1703 if (r == 0 && key != NULL && 1704 (r = sshkey_shield_private(key)) != 0) { 1705 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1706 options.host_key_files[i]); 1707 sshkey_free(key); 1708 key = NULL; 1709 } 1710 if ((r = sshkey_load_public(options.host_key_files[i], 1711 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1712 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1713 options.host_key_files[i]); 1714 if (pubkey != NULL && key != NULL) { 1715 if (!sshkey_equal(pubkey, key)) { 1716 error("Public key for %s does not match " 1717 "private key", options.host_key_files[i]); 1718 sshkey_free(pubkey); 1719 pubkey = NULL; 1720 } 1721 } 1722 if (pubkey == NULL && key != NULL) { 1723 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1724 fatal_r(r, "Could not demote key: \"%s\"", 1725 options.host_key_files[i]); 1726 } 1727 sensitive_data.host_keys[i] = key; 1728 sensitive_data.host_pubkeys[i] = pubkey; 1729 1730 if (key == NULL && pubkey != NULL && have_agent) { 1731 debug("will rely on agent for hostkey %s", 1732 options.host_key_files[i]); 1733 keytype = pubkey->type; 1734 } else if (key != NULL) { 1735 keytype = key->type; 1736 accumulate_host_timing_secret(cfg, key); 1737 } else { 1738 do_log2(ll, "Unable to load host key: %s", 1739 options.host_key_files[i]); 1740 sensitive_data.host_keys[i] = NULL; 1741 sensitive_data.host_pubkeys[i] = NULL; 1742 continue; 1743 } 1744 1745 switch (keytype) { 1746 case KEY_RSA: 1747 case KEY_DSA: 1748 case KEY_ECDSA: 1749 case KEY_ED25519: 1750 case KEY_ECDSA_SK: 1751 case KEY_ED25519_SK: 1752 case KEY_XMSS: 1753 if (have_agent || key != NULL) 1754 sensitive_data.have_ssh2_key = 1; 1755 break; 1756 } 1757 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1758 SSH_FP_DEFAULT)) == NULL) 1759 fatal("sshkey_fingerprint failed"); 1760 debug("%s host key #%d: %s %s", 1761 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1762 free(fp); 1763 } 1764 accumulate_host_timing_secret(cfg, NULL); 1765 if (!sensitive_data.have_ssh2_key) { 1766 logit("sshd: no hostkeys available -- exiting."); 1767 exit(1); 1768 } 1769 1770 /* 1771 * Load certificates. They are stored in an array at identical 1772 * indices to the public keys that they relate to. 1773 */ 1774 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1775 sizeof(struct sshkey *)); 1776 for (i = 0; i < options.num_host_key_files; i++) 1777 sensitive_data.host_certificates[i] = NULL; 1778 1779 for (i = 0; i < options.num_host_cert_files; i++) { 1780 if (options.host_cert_files[i] == NULL) 1781 continue; 1782 if ((r = sshkey_load_public(options.host_cert_files[i], 1783 &key, NULL)) != 0) { 1784 error_r(r, "Could not load host certificate \"%s\"", 1785 options.host_cert_files[i]); 1786 continue; 1787 } 1788 if (!sshkey_is_cert(key)) { 1789 error("Certificate file is not a certificate: %s", 1790 options.host_cert_files[i]); 1791 sshkey_free(key); 1792 continue; 1793 } 1794 /* Find matching private key */ 1795 for (j = 0; j < options.num_host_key_files; j++) { 1796 if (sshkey_equal_public(key, 1797 sensitive_data.host_keys[j])) { 1798 sensitive_data.host_certificates[j] = key; 1799 break; 1800 } 1801 } 1802 if (j >= options.num_host_key_files) { 1803 error("No matching private key for certificate: %s", 1804 options.host_cert_files[i]); 1805 sshkey_free(key); 1806 continue; 1807 } 1808 sensitive_data.host_certificates[j] = key; 1809 debug("host certificate: #%u type %d %s", j, key->type, 1810 sshkey_type(key)); 1811 } 1812 1813 if (use_privsep) { 1814 struct stat st; 1815 1816 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1817 fatal("Privilege separation user %s does not exist", 1818 SSH_PRIVSEP_USER); 1819 endpwent(); 1820 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1821 (S_ISDIR(st.st_mode) == 0)) 1822 fatal("Missing privilege separation directory: %s", 1823 _PATH_PRIVSEP_CHROOT_DIR); 1824 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1825 fatal("%s must be owned by root and not group or " 1826 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1827 } 1828 1829 if (test_flag > 1) { 1830 /* 1831 * If no connection info was provided by -C then use 1832 * use a blank one that will cause no predicate to match. 1833 */ 1834 if (connection_info == NULL) 1835 connection_info = get_connection_info(ssh, 0, 0); 1836 connection_info->test = 1; 1837 parse_server_match_config(&options, &includes, connection_info); 1838 dump_config(&options); 1839 } 1840 1841 /* Configuration looks good, so exit if in test mode. */ 1842 if (test_flag) 1843 exit(0); 1844 1845 if (rexec_flag) { 1846 if (rexec_argc < 0) 1847 fatal("rexec_argc %d < 0", rexec_argc); 1848 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1849 for (i = 0; i < (u_int)rexec_argc; i++) { 1850 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1851 rexec_argv[i] = saved_argv[i]; 1852 } 1853 rexec_argv[rexec_argc] = "-R"; 1854 rexec_argv[rexec_argc + 1] = NULL; 1855 } 1856 listener_proctitle = prepare_proctitle(ac, av); 1857 1858 /* Ensure that umask disallows at least group and world write */ 1859 new_umask = umask(0077) | 0022; 1860 (void) umask(new_umask); 1861 1862 /* Initialize the log (it is reinitialized below in case we forked). */ 1863 if (debug_flag && (!inetd_flag || rexeced_flag)) 1864 log_stderr = 1; 1865 log_init(__progname, options.log_level, 1866 options.log_facility, log_stderr); 1867 for (i = 0; i < options.num_log_verbose; i++) 1868 log_verbose_add(options.log_verbose[i]); 1869 1870 /* 1871 * If not in debugging mode, not started from inetd and not already 1872 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1873 * terminal, and fork. The original process exits. 1874 */ 1875 already_daemon = daemonized(); 1876 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1877 1878 if (daemon(0, 0) == -1) 1879 fatal("daemon() failed: %.200s", strerror(errno)); 1880 1881 disconnect_controlling_tty(); 1882 } 1883 /* Reinitialize the log (because of the fork above). */ 1884 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1885 1886 /* Chdir to the root directory so that the current disk can be 1887 unmounted if desired. */ 1888 if (chdir("/") == -1) 1889 error("chdir(\"/\"): %s", strerror(errno)); 1890 1891 /* ignore SIGPIPE */ 1892 ssh_signal(SIGPIPE, SIG_IGN); 1893 1894 /* Get a connection, either from inetd or a listening TCP socket */ 1895 if (inetd_flag) { 1896 server_accept_inetd(&sock_in, &sock_out); 1897 } else { 1898 server_listen(); 1899 1900 ssh_signal(SIGHUP, sighup_handler); 1901 ssh_signal(SIGCHLD, main_sigchld_handler); 1902 ssh_signal(SIGTERM, sigterm_handler); 1903 ssh_signal(SIGQUIT, sigterm_handler); 1904 1905 /* 1906 * Write out the pid file after the sigterm handler 1907 * is setup and the listen sockets are bound 1908 */ 1909 if (options.pid_file != NULL && !debug_flag) { 1910 FILE *f = fopen(options.pid_file, "w"); 1911 1912 if (f == NULL) { 1913 error("Couldn't create pid file \"%s\": %s", 1914 options.pid_file, strerror(errno)); 1915 } else { 1916 fprintf(f, "%ld\n", (long) getpid()); 1917 fclose(f); 1918 } 1919 } 1920 1921 /* Accept a connection and return in a forked child */ 1922 server_accept_loop(&sock_in, &sock_out, 1923 &newsock, config_s); 1924 } 1925 1926 /* This is the child processing a new connection. */ 1927 setproctitle("%s", "[accepted]"); 1928 1929 /* 1930 * Create a new session and process group since the 4.4BSD 1931 * setlogin() affects the entire process group. We don't 1932 * want the child to be able to affect the parent. 1933 */ 1934 if (!debug_flag && !inetd_flag && setsid() == -1) 1935 error("setsid: %.100s", strerror(errno)); 1936 1937 if (rexec_flag) { 1938 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1939 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1940 dup2(newsock, STDIN_FILENO); 1941 dup2(STDIN_FILENO, STDOUT_FILENO); 1942 if (startup_pipe == -1) 1943 close(REEXEC_STARTUP_PIPE_FD); 1944 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1945 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1946 close(startup_pipe); 1947 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1948 } 1949 1950 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1951 close(config_s[1]); 1952 1953 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1954 execv(rexec_argv[0], rexec_argv); 1955 1956 /* Reexec has failed, fall back and continue */ 1957 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1958 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1959 log_init(__progname, options.log_level, 1960 options.log_facility, log_stderr); 1961 1962 /* Clean up fds */ 1963 close(REEXEC_CONFIG_PASS_FD); 1964 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1965 if (stdfd_devnull(1, 1, 0) == -1) 1966 error_f("stdfd_devnull failed"); 1967 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1968 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1969 } 1970 1971 /* Executed child processes don't need these. */ 1972 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1973 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1974 1975 /* We will not restart on SIGHUP since it no longer makes sense. */ 1976 ssh_signal(SIGALRM, SIG_DFL); 1977 ssh_signal(SIGHUP, SIG_DFL); 1978 ssh_signal(SIGTERM, SIG_DFL); 1979 ssh_signal(SIGQUIT, SIG_DFL); 1980 ssh_signal(SIGCHLD, SIG_DFL); 1981 1982 /* 1983 * Register our connection. This turns encryption off because we do 1984 * not have a key. 1985 */ 1986 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 1987 fatal("Unable to create connection"); 1988 the_active_state = ssh; 1989 ssh_packet_set_server(ssh); 1990 1991 check_ip_options(ssh); 1992 1993 /* Prepare the channels layer */ 1994 channel_init_channels(ssh); 1995 channel_set_af(ssh, options.address_family); 1996 process_permitopen(ssh, &options); 1997 1998 /* Set SO_KEEPALIVE if requested. */ 1999 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2000 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2001 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2002 2003 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2004 debug("ssh_remote_port failed"); 2005 cleanup_exit(255); 2006 } 2007 2008 /* 2009 * The rest of the code depends on the fact that 2010 * ssh_remote_ipaddr() caches the remote ip, even if 2011 * the socket goes away. 2012 */ 2013 remote_ip = ssh_remote_ipaddr(ssh); 2014 2015 rdomain = ssh_packet_rdomain_in(ssh); 2016 2017 /* Log the connection. */ 2018 laddr = get_local_ipaddr(sock_in); 2019 verbose("Connection from %s port %d on %s port %d%s%s%s", 2020 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2021 rdomain == NULL ? "" : " rdomain \"", 2022 rdomain == NULL ? "" : rdomain, 2023 rdomain == NULL ? "" : "\""); 2024 free(laddr); 2025 2026 /* 2027 * We don't want to listen forever unless the other side 2028 * successfully authenticates itself. So we set up an alarm which is 2029 * cleared after successful authentication. A limit of zero 2030 * indicates no limit. Note that we don't set the alarm in debugging 2031 * mode; it is just annoying to have the server exit just when you 2032 * are about to discover the bug. 2033 */ 2034 ssh_signal(SIGALRM, grace_alarm_handler); 2035 if (!debug_flag) 2036 alarm(options.login_grace_time); 2037 2038 if ((r = kex_exchange_identification(ssh, -1, 2039 options.version_addendum)) != 0) 2040 sshpkt_fatal(ssh, r, "banner exchange"); 2041 2042 ssh_packet_set_nonblocking(ssh); 2043 2044 /* allocate authentication context */ 2045 authctxt = xcalloc(1, sizeof(*authctxt)); 2046 ssh->authctxt = authctxt; 2047 2048 /* XXX global for cleanup, access from other modules */ 2049 the_authctxt = authctxt; 2050 2051 /* Set default key authentication options */ 2052 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2053 fatal("allocation failed"); 2054 2055 /* prepare buffer to collect messages to display to user after login */ 2056 if ((loginmsg = sshbuf_new()) == NULL) 2057 fatal_f("sshbuf_new failed"); 2058 auth_debug_reset(); 2059 2060 if (use_privsep) { 2061 if (privsep_preauth(ssh) == 1) 2062 goto authenticated; 2063 } else if (have_agent) { 2064 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2065 error_r(r, "Unable to get agent socket"); 2066 have_agent = 0; 2067 } 2068 } 2069 2070 /* perform the key exchange */ 2071 /* authenticate user and start session */ 2072 do_ssh2_kex(ssh); 2073 do_authentication2(ssh); 2074 2075 /* 2076 * If we use privilege separation, the unprivileged child transfers 2077 * the current keystate and exits 2078 */ 2079 if (use_privsep) { 2080 mm_send_keystate(ssh, pmonitor); 2081 ssh_packet_clear_keys(ssh); 2082 exit(0); 2083 } 2084 2085 authenticated: 2086 /* 2087 * Cancel the alarm we set to limit the time taken for 2088 * authentication. 2089 */ 2090 alarm(0); 2091 ssh_signal(SIGALRM, SIG_DFL); 2092 authctxt->authenticated = 1; 2093 if (startup_pipe != -1) { 2094 close(startup_pipe); 2095 startup_pipe = -1; 2096 } 2097 2098 if (options.routing_domain != NULL) 2099 set_process_rdomain(ssh, options.routing_domain); 2100 2101 /* 2102 * In privilege separation, we fork another child and prepare 2103 * file descriptor passing. 2104 */ 2105 if (use_privsep) { 2106 privsep_postauth(ssh, authctxt); 2107 /* the monitor process [priv] will not return */ 2108 } 2109 2110 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2111 options.client_alive_count_max); 2112 2113 /* Try to send all our hostkeys to the client */ 2114 notify_hostkeys(ssh); 2115 2116 /* Start session. */ 2117 do_authenticated(ssh, authctxt); 2118 2119 /* The connection has been terminated. */ 2120 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2121 verbose("Transferred: sent %llu, received %llu bytes", 2122 (unsigned long long)obytes, (unsigned long long)ibytes); 2123 2124 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2125 ssh_packet_close(ssh); 2126 2127 if (use_privsep) 2128 mm_terminate(); 2129 2130 exit(0); 2131 } 2132 2133 int 2134 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2135 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2136 const u_char *data, size_t dlen, const char *alg) 2137 { 2138 int r; 2139 2140 if (use_privsep) { 2141 if (privkey) { 2142 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2143 data, dlen, alg, options.sk_provider, NULL, 2144 ssh->compat) < 0) 2145 fatal_f("privkey sign failed"); 2146 } else { 2147 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2148 data, dlen, alg, options.sk_provider, NULL, 2149 ssh->compat) < 0) 2150 fatal_f("pubkey sign failed"); 2151 } 2152 } else { 2153 if (privkey) { 2154 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2155 alg, options.sk_provider, NULL, ssh->compat) < 0) 2156 fatal_f("privkey sign failed"); 2157 } else { 2158 if ((r = ssh_agent_sign(auth_sock, pubkey, 2159 signature, slenp, data, dlen, alg, 2160 ssh->compat)) != 0) { 2161 fatal_fr(r, "agent sign failed"); 2162 } 2163 } 2164 } 2165 return 0; 2166 } 2167 2168 /* SSH2 key exchange */ 2169 static void 2170 do_ssh2_kex(struct ssh *ssh) 2171 { 2172 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2173 struct kex *kex; 2174 int r; 2175 2176 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2177 options.kex_algorithms); 2178 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2179 options.ciphers); 2180 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2181 options.ciphers); 2182 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2183 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2184 2185 if (options.compression == COMP_NONE) { 2186 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2187 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2188 } 2189 2190 if (options.rekey_limit || options.rekey_interval) 2191 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2192 options.rekey_interval); 2193 2194 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2195 list_hostkey_types()); 2196 2197 /* start key exchange */ 2198 if ((r = kex_setup(ssh, myproposal)) != 0) 2199 fatal_r(r, "kex_setup"); 2200 kex = ssh->kex; 2201 #ifdef WITH_OPENSSL 2202 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2203 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2204 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2205 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2206 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2207 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2208 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2209 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2210 #endif 2211 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2212 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2213 kex->load_host_public_key=&get_hostkey_public_by_type; 2214 kex->load_host_private_key=&get_hostkey_private_by_type; 2215 kex->host_key_index=&get_hostkey_index; 2216 kex->sign = sshd_hostkey_sign; 2217 2218 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2219 2220 session_id2 = kex->session_id; 2221 session_id2_len = kex->session_id_len; 2222 2223 #ifdef DEBUG_KEXDH 2224 /* send 1st encrypted/maced/compressed message */ 2225 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2226 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2227 (r = sshpkt_send(ssh)) != 0 || 2228 (r = ssh_packet_write_wait(ssh)) != 0) 2229 fatal_fr(r, "send test"); 2230 #endif 2231 debug("KEX done"); 2232 } 2233 2234 /* server specific fatal cleanup */ 2235 void 2236 cleanup_exit(int i) 2237 { 2238 if (the_active_state != NULL && the_authctxt != NULL) { 2239 do_cleanup(the_active_state, the_authctxt); 2240 if (use_privsep && privsep_is_preauth && 2241 pmonitor != NULL && pmonitor->m_pid > 1) { 2242 debug("Killing privsep child %d", pmonitor->m_pid); 2243 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2244 errno != ESRCH) { 2245 error_f("kill(%d): %s", pmonitor->m_pid, 2246 strerror(errno)); 2247 } 2248 } 2249 } 2250 _exit(i); 2251 } 2252